Delkin’s Battery Tester & Carrying Case not only accurately tests both AA and AAA batteries for remaining power, but acts as a protective carrying case for batteries as well. The carrying case can hold up to four AA or AAA batteries at a time. The only power required to run the tester is supplied by the battery inserted into the tester slot – no adapters required. A switch allows the user to test either primary or rechargeable batteries, and LED lights quickly indicate how much power is remaining once a battery is inserted. The tester is designed to be small, lightweight, and portable so that it fits easily into your camera bag. Two year limited warranty.